Surgical instrument including an adapter assembly and an articulating surgical loading unit

ABSTRACT

An adapter assembly of a surgical instrument includes a cam member defining a proximal cam slot and a distal cam slot, a first articulation shaft, and a second articulation shaft. The first articulation shaft has a proximal end portion received in the proximal cam slot, and a distal end portion configured to be coupled to a surgical loading unit. The second articulation shaft has a proximal end portion received in the distal cam slot, and a distal end portion configured to be coupled to the surgical loading unit. The first and second articulation shafts are configured to move in opposing longitudinal directions in response to a rotation of the cam member to articulate the surgical loading unit.

BACKGROUND Technical Field

The disclosure relates generally to surgical instruments for endoscopicuse and, more specifically, to surgical instruments including adapterassemblies that articulate an attached surgical loading unit.

Background of Related Art

Various types of surgical instruments used to endoscopically treattissue are known in the art, and are commonly used, for example, forclosure of tissue or organs in transection, resection, anastomoses, forocclusion of organs in thoracic and abdominal procedures, and forelectrosurgically fusing or sealing tissue.

One example of such a surgical instrument is a surgical staplinginstrument. Typically, surgical stapling instruments include an endeffector having an anvil assembly and a cartridge assembly forsupporting an array of surgical staples, an approximation mechanism forapproximating the cartridge and anvil assemblies, and a firing mechanismfor ejecting the surgical staples from the cartridge assembly.

During laparoscopic or endoscopic surgical procedures, access to asurgical site is achieved through a small incision or through a narrowcannula inserted through a small entrance wound in a patient. Because oflimited area available to access the surgical site, many endoscopicinstruments include mechanisms for articulating the end effector of theinstrument in relation to a body portion of the instrument to improveaccess to tissue to be treated.

SUMMARY

In an aspect of the disclosure, an adapter assembly includes a cammember defining a first cam slot and a second cam slot, an outer tubeextending distally from the cam member and having a distal end portionconfigured to be coupled to a surgical loading unit, and first andsecond articulation shafts each having a proximal end portion and adistal end portion. The proximal end portion of the first articulationshaft is operably coupled to the proximal cam slot of the cam member andthe proximal end portion of the second articulation shaft is operablycoupled to the distal cam slot of the cam member. The distal end portionof each of the first and second articulation shafts is configured to becoupled to the surgical loading unit. The first and second articulationshafts are configured to translate in opposite directions in response toa rotation of the cam member to articulate the surgical loading unitrelative to the outer tube.

In aspects, the adapter assembly may further include a proximal ringmember and a distal ring member each disposed about the cam member. Theproximal ring member may have a projection received in the first camslot, and the distal ring member may have a projection received in thesecond cam slot. The proximal and distal ring members may be configuredto move axially in opposite longitudinal directions in response to therotation of the cam member.

In aspects, the proximal end portion of the first articulation shaft maybe axially restrained to the proximal ring member, and the proximal endportion of the second articulation shaft may be axially restrained tothe distal ring member. The first and second articulation shafts may beconfigured to move axially with the respective proximal and distal ringmembers.

In aspects, the first and second articulation shafts may be rotatablerelative to and about the respective proximal and distal ring members.

In aspects, the proximal ring member may define an outer annular groovetherein, and the proximal end portion of the first articulation shaftmay have an annular protrusion slidably received in the annular groove.The distal ring member may define an outer annular groove therein, andthe proximal end portion of the second articulation shaft may have anannular protrusion slidably received in the annular groove of the distalring member.

In aspects, the adapter assembly may further include a knob housingdisposed about a proximal end portion of the outer tube. The proximalend portion of each of the first and second articulation shafts may benon-rotationally coupled to the knob housing and axially movablerelative to the knob housing.

In aspects, the knob housing may include an inner surface defining apair of longitudinally-extending slots, and the proximal end portion ofeach of the first and second articulation shafts may have alongitudinally-extending ridge received in the respective pair oflongitudinally-extending slots of the knob housing.

In aspects, the proximal end portion of the first articulation shaft mayhave an inwardly-extending protrusion, and the distal end portion of theouter tube may define a longitudinally-extending slot having receivedtherein the protrusion of the first articulation shaft, such that thedistal end portion of the outer tube rotates with the first articulationshaft about the longitudinal axis in response to a rotation of the knobhousing.

In aspects, the proximal end portion of each of the first and secondarticulation shafts may be disposed about the outer tube and the cammember.

In accordance with another aspect of the disclosure, a surgicalinstrument is provided and includes a surgical loading unit and anadapter assembly. The adapter assembly includes a coupling mechanismhaving a drive shaft, a cam member operably coupled to the drive shaftand defining a proximal cam slot and a distal cam slot, an outer tubeextending distally from the cam member and having a distal end portionconfigured to be coupled to the surgical loading unit, and first andsecond articulation shafts each having a proximal end portion and adistal end portion. The proximal end portion of the first articulationshaft is operably coupled to the proximal cam slot of the cam member andthe proximal end portion of the second articulation shaft is operablycoupled to the distal cam slot of the cam member. The distal end portionof each of the first and second articulation shafts is configured to becoupled to the surgical loading unit. The first and second articulationshafts are configured to translate in opposite directions in response toa rotation of the cam member to articulate the surgical loading unitrelative to the outer tube.

In aspects, the adapter assembly may further include a knob housingrotationally coupled to the coupling mechanism and disposed about aproximal end portion of the outer tube. The proximal end portion of eachof the first and second articulation shafts may be non-rotationallycoupled to the knob housing and axially movable relative to the knobhousing.

In aspects, the proximal end portion of each of the first and secondarticulation shafts may be curved and disposed about the outer tube andthe cam member.

BRIEF DESCRIPTION OF THE DRAWINGS

Surgical instruments including exemplary aspects of the the disclosedadapter assemblies are disclosed herein with reference to the drawings,wherein:

FIG. 1 is a perspective view of a surgical instrument including a handleassembly, an adapter assembly, and a surgical loading unit;

FIG. 2 is a perspective view of the adapter assembly and the surgicalloading unit of FIG. 1;

FIG. 3 is a perspective view of internal components of the adapterassembly of FIG. 2 including a coupling mechanism, an outer tube, a pairof ring members, and a pair of articulation shafts;

FIG. 4 is a perspective view, with parts separated, of the adapterassembly of FIG. 3;

FIG. 5 is a side perspective view illustrating the adapter assembly ofFIG. 3, with a portion of the outer tube, the pair of articulationshafts, and the pair of ring members removed to better illustrate adrive assembly and a cam member;

FIG. 6 is a side perspective view illustrating the adapter assembly ofFIG. 3, with a portion of the outer tube and the pair of articulationshafts removed;

FIG. 7 is a side perspective view illustrating the adapter assembly ofFIG. 3, with the pair of articulation shafts removed;

FIG. 8 is a longitudinal cross-sectional view illustrating the surgicalloading unit of FIG. 1 in an articulated position;

FIG. 9 is a side perspective view illustrating the surgical loading unitof FIG. 1 in the articulated position;

FIG. 10 is a longitudinal cross sectional view of the adapter assemblyof FIG. 3 illustrating the pair of articulation shafts in anon-articulated position; and

FIG. 11 is a longitudinal cross sectional view of the adapter assemblyof FIG. 3 illustrating the pair of articulation shafts in an articulatedposition.

DETAILED DESCRIPTION

As used herein, the term “distal” refers to that portion of the surgicalinstrument which is farthest from a clinician, while the term “proximal”refers to that portion of the surgical instrument which is closest tothe clinician. In addition, as used herein, the term clinician refers tomedical staff including doctors, nurses and support personnel.

The disclosure is directed to a surgical instrument including an adapterassembly configured to be actuated by a hand-held actuator or a surgicalrobotic system, and a surgical loading unit coupled to the adapterassembly. The adapter assembly includes an articulation mechanism thatdrives an articulation of the surgical loading unit relative to theadapter assembly. The articulation mechanism includes a rotatable cammember that defines a pair of cam slots, each of which receiving acorresponding pin of a pair of ring members. As the cam member rotates,the cam slots drive an opposing longitudinal motion of the pair of ringmembers, which translate first and second articulation shafts inopposing longitudinal directions. Translation of the articulation shaftsin opposite longitudinal directions articulates the surgical loadingunit relative to an outer tube of the adapter assembly. Additionaladvantages of the disclosed surgical instruments and components thereofare described below.

FIGS. 1 and 2 depict a surgical instrument 10 including a handleassembly 12, an adapter assembly 20 configured to be coupled to thehandle assembly 12, and a surgical loading unit 30 pivotably coupled tothe adapter assembly 20. While the depicted surgical instrument 10 maybe configured to fire staples, it is contemplated that the surgicalinstrument 10 may be adapted to fire any other suitable fastener such asclips and two-part fasteners. Additionally, while the figures depict alinear surgical stapling instrument 10, it is envisioned that certaincomponents described herein may be adapted for use in other types ofendoscopic surgical instruments including non-linear surgical staplerloading units, endoscopic forceps, graspers, dissectors, other types ofsurgical stapling instruments, powered vessel sealing and/or cuttingdevices, etc.

As shown in FIGS. 2-4, the adapter assembly 20 of the surgicalinstrument 10 includes a coupling mechanism 14, an outer tube 24extending distally from the coupling assembly 14, and an outer housing,such as, for example, a rotatable knob housing 21 for manually rotatinga distal end portion 24 b of the outer tube 24 and the attached surgicalloading unit 30. The coupling mechanism 14 is configured to be operablycoupled to the handle assembly 12 or a surgical robotic system (notshown) responsible for actuating the surgical instrument 10. Thecoupling mechanism 14 has a proximal housing 14 a (FIG. 3) configured tocouple to a distal half-section 13 (FIG. 1) of the handle assembly 12, adistal cap 14 b attached to the proximal housing, and a plurality ofdrive assemblies supported in the proximal housing 14 a for transferringactuation forces from motors (not explicitly shown) of the handleassembly 12 to the surgical loading unit 30. For example, one of thedrive assemblies is an articulation drive assembly 100 (FIG. 4)including a drive shaft 102 and a rotation gear 104. The drive shaft 102is rotatably supported by the proximal housing 14 a and is configured toreceive actuation forces from one of the drive motors of the handleassembly 12. The drive shaft 102 supports a gear 106, such as, forexample, a pinion gear that is in meshing engagement with the rotationgear 104 (e.g., a spur gear). The rotation gear 104 is disposed aboutand fixed to a cam 108 of the adapter assembly 20. In aspects, variousalternate types of gears and/or drive transfer mechanisms may beprovided, such as, for example, belt drives, miter gears, bevel gears,helical gears, screw gears, or the like.

The outer tube 24 (FIG. 2) of the adapter assembly 20 may be an assemblyincluding a proximal tube 24 a (FIG. 3) disposed within the knob housing21 and a distal tube 24 b connected to the proximal tube 24 a. Theproximal tube 24 a is rotationally and axially fixed to the couplingmechanism 14, and the distal tube 24 b is configured to rotate withrespect to the proximal tube 24 a and with the knob housing 21 about alongitudinal axis “X” (FIG. 2) defined by the outer tube 24.

FIGS. 3-5 illustrate the cam member 108, which may be a tubular shaft orhousing that extends through and is rotationally supported in theproximal tube 14 a of the outer tube assembly 24. The cam member 108 maybe pinned or otherwise non-rotationally coupled to the rotation gear 104of the coupling mechanism 14, such that the cam member 108 rotates witha rotation of the rotation gear 104. The cam member 108 has a tubularouter surface defining a proximal cam slot 108 a and a distal cam slot108 b therein. The proximal and distal cam slots 108 a, 108 b arelongitudinally spaced from one another and wrap around a centrallongitudinal axis defined by the cam member 108. The proximal and distalcam slots 108 a, 108 b each have opposite helical configurations. Forexample, the proximal cam slot 108 a may have a left-handed helicalconfiguration, whereas the distal cam slot 108 b may have a right-handedhelical configuration, or vice versa. In aspects, the proximal anddistal cam slots 108 a, 108 b may each have the same handedness, such asleft-handedness or right-handedness.

With reference to FIGS. 3, 4, 6, and 7, the adapter assembly 20 furtherincludes a pair of proximal and distal ring members 110, 112 operablycoupled to the cam member 108, a pair of articulation shafts 120, 122operably coupled to the ring members 110, 112, and a pair ofarticulation links 150, 152 (FIG. 8) operably coupling the articulationshafts 120, 122 with the surgical loading unit 30. The proximal anddistal ring members 110, 112 are each disposed about the proximal tube24 a, with each having a ring body 110 a, 112 a and a projection 110 b,112 b, such as, for example, a pin, extending radially inward from thering body 110 a, 112 a. The ring body 110 a, 112 a of each of the ringmembers 110, 112 defines an annular groove 114, 116 in an outer surfacethereof. A flexible ring-shaped snap retainer 118, 124 may be receivedin the annular groove 114, 116 to maintain the projections 110 b, 112 bfixed to the ring bodies 1120 a, 112 a.

The projection 110 b of the proximal ring member 110 extends through afirst longitudinally-extending guide slot 126 (FIG. 7) in the proximaltube 24 a and is received in the proximal cam slot 108 a of the cammember 108. The projection 112 b of the distal ring member 112 extendsthrough a second longitudinally-extending guide slot (not explicitlyshown) in the proximal tube 24 a and is received in the distal cam slot108 b of the cam member 108. The first and second guide slots 126 aredisposed on opposite lateral sides of the proximal tube 24 a and ensurethat the proximal and distal ring members 110, 112 do not rotate duringrotation of the cam member 108. Due to the projections 110 b, 112 b ofthe proximal and distal ring members 110, 112 being received in therespective proximal and distal cam slots 108 a, 108 b of the cam member108, rotation of the cam member 108 translates the proximal and distalring members 110, 112 in opposite directions along the longitudinal axis“X” of the outer tube 24.

As best shown in FIGS. 3 and 4, the left articulation shaft 120 includesa proximal end portion, such as, for example, a left housing half 120 ahaving a semi-cylindrical configuration, and a distal end portion, suchas, for example, an elongate bar 120 b extending distally from the lefthousing half 120 a. Similarly, the right articulation shaft 122 includesa proximal end portion, such as, for example, a right housing half 122 ahaving a semi-cylindrical configuration, and a distal end portion, suchas, for example, an elongate bar 122 b extending distally from the righthousing half 122 a. The right housing half 122 a may be longer than theleft housing half 120 a, as will be described.

Each of the housing halves 120 a, 122 a of the left and rightarticulation shafts 120, 122 has an inwardly-extending, annularprotrusion 134, 136 disposed at a proximal end thereof. The annularprotrusion 134 of the left housing half 120 a is slidably received inthe annular groove 114 of the distal ring member 112 due to the lefthousing half 120 a being shorter than the right housing half 122 a. Theannular protrusion 136 of the right housing half 122 a is slidablyreceived in the annular groove 116 of the proximal ring member 110. Assuch, longitudinal motion of the proximal and distal ring members 110 a,112 is transferred to the respective right and left articulation shafts122, 120 while allowing for the right and left articulation shafts 122,120 to rotate about the proximal and distal ring members 110, 112 andwith the knob housing 21 (FIG. 4).

An outer surface of each of the housing halves 120 a, 122 a has alongitudinally-extending ridge 128 (the ridge of the right housing half122 a is not explicitly shown) extending outwardly. Each of the ridges128 is slidably received in a corresponding longitudinally-extendingchannel or slot 130 defined in an inner surface 132 of the knob housing21. The engagement of the ridges 128 of the left and right housinghalves 120 a, 122 a with the channels 130 defined in the opposite sidesof the knob housing 21 allows for the left and right articulation shafts120, 122 to translate relative to and within the knob housing 21 whilealso forming a non-rotatable engagement with the knob housing 21 suchthat the articulation shafts 120, 122 are rotatable with the knobhousing 21.

The left and right housing halves 120 a, 122 a of the left and rightarticulation shafts 120, 122 each further include an inwardly-extendingprojection or tab 138, 140 (FIG. 3) that extend through respective leftand right longitudinally-extending guide slots 144 a, 144 b defined inthe distal tube 24 b. The guide slots 144 a, 144 b in the distal tube 24b allow for the left and right housing halves 120 a, 122 a to translaterelative to the distal tube 24 b while non-rotationally coupling theleft and right housing halves 120 a, 122 to the distal tube 24 b.

With reference to FIGS. 4, 8, and 9, each of the elongate bars 120 b,122 b of the left and right articulation shafts 120, 122 has a proximalend portion 146 a, 148 a and a distal end portion 146 b, 148 b. Theproximal end portion 146 a, 148 a of each of the elongate bars 120 b,122 b defines an opening having received therein the respective tab 138,140 of the left and right housing halves 120 a, 122 a to axially fix theleft housing half 120 a to the left elongate bar 120 b and axially fixthe right housing half 122 a to the right elongate bar 122 b. The leftand right elongate bars 120 b, 122 b of the respective left and rightarticulation shafts 120, 122 extend distally through the distal tube 24b and terminate distally at a distal end of the distal tube 24 b.

The first articulation link 150 (FIG. 8) has a proximal end portion 150a pivotably coupled to the distal end portion 146 b of the left elongatebar 120 b, and the second articulation link 152 has a proximal endportion 152 a pivotably coupled to the distal end portion 148 b of theright elongate bar 122 b. In aspects, the first and second articulationlinks 150, 152 may be coupled to the first and second elongate bars 120b, 122 b via intermediary shafts (not explicitly shown). The first andsecond links 150, 152 each have a distal end portion 150 b, 152 bpivotably coupled to opposite sides of a collar 32 of the surgicalloading unit 30. As such, the opposing longitudinal motion of the firstand second articulation shafts 120, 122, induced by a rotation of thecam member 108, pushes and pulls the corresponding first and secondlinks 150, 152 to articulate the surgical loading unit 30 relative tothe adapter assembly 20.

The surgical loading unit 30 is adapted to be attached to the distaltube 24 b of the adapter assembly 20 and may be configured for a singleuse, or may be configured to be used more than once. A pivot joint 26(FIG. 9) is pivotably coupled to the distal tube 24 b and axiallyrestrained thereto. The pivot joint 26 is configured to pivotablysupport the collar 32 of the surgical loading unit 30 thereto. Thesurgical loading unit 30 includes an end effector 34 supported on thecollar 32. The end effector 34 includes an anvil plate 36non-rotationally coupled to the collar 32, and a staple cartridgeassembly 37 disposed in opposed relation with the anvil plate 36. Thestaple cartridge assembly 37 has a chassis 38 pivotably coupled to thecollar 32 and a staple cartridge body 40 configured for removablereceipt in a channel of the chassis 38. A knife rod (not explicitlyshown) is translatable through the end effector 34 to cut tissuedisposed therebetween. The knife rod is further configured toselectively open and close the end effector 34 and fire staplestherefrom as it translates through the end effector 34.

In operation, with reference to FIGS. 10 and 11, to articulate thesurgical loading unit 30, the drive shaft 102 of the articulation driveassembly 100 is rotated via an actuation of the handle assembly 12 (FIG.1). The drive shaft 102 transfers rotational motion from the gear 106fixed thereabout to the rotation gear 104. Since the cam member 108 isfixed to the rotation gear 104 (FIG. 5), the cam member 108 rotates withthe rotation gear 104 about the central longitudinal axis “X” of theouter tube 24. As the cam member 108 rotates, the proximal cam slot 108a of the cam member 108 drives the pin 110 a of the proximal ring member110 through the proximal cam slot 108 a in a proximal direction and thedistal cam slot 108 b of the cam member 108 drives the pin 112 b of thedistal ring member 112 through the distal cam slot 108 b in a distaldirection.

The proximal movement of the proximal ring member 110 drives a proximalmovement of the right articulation shaft 122, in the direction indicatedby arrow “A” in FIG. 10, due to the engagement of the right housing half122 a of the right articulation shaft 122 with the proximal ring member110. Similarly, the distal movement of the distal ring member 112 drivesa distal movement of the left articulation shaft 120, in the directionindicated by arrow “B” in FIG. 10, due to the engagement of the lefthousing half 120 a of the left articulation shaft 120 with the distalring member 112. As such, the right and left articulation shafts 122,120 are moved from a first position (FIG. 10) corresponding to anon-articulated orientation of the surgical loading unit 30 (i.e., thesurgical loading unit 30 is coaxial with the outer tube 24) to a secondposition (FIG. 11) corresponding to an articulated orientation of thesurgical loading unit 30 (i.e., the surgical loading unit 30 is pivotedto a non-parallel angle relative to the outer tube 24, FIG. 9).

In particular, due to the first articulation link 150 acting as apivotable coupling between the left articulation shaft 120 of theadapter assembly 20 and the left side of the surgical loading unit 30,and the second articulation link 152 acting as a pivotable couplingbetween the right articulation shaft 122 of the adapter assembly 20 andthe right side of the surgical loading unit 30, proximal movement of theright articulation shaft 122 and distal movement of the leftarticulation shaft 120 drives an articulation of the surgical loadingunit 30 in the right direction indicated by arrow “C” in FIG. 9. It iscontemplated that a rotation of the cam member 108 in the oppositedirection results in an articulation of the surgical loading unit 30 inthe left direction.

To rotate the surgical loading unit 30 about the longitudinal axis “X”of the outer tube 24, the knob housing 21 may be manually rotated aboutthe longitudinal axis “X.” Since the ridge 128 (FIG. 3) of the lefthousing half 120 a is captured in the left channel (not shown) in theknob housing 21, and the ridge (not shown) of the right housing half 122a is captured in the right channel 130 (FIG. 4) in the knob housing 21,the left and right articulation shafts 120, 122 rotate with the rotationof the knob housing 21. The arcuate grooves 114, 116 in the proximal anddistal ring members 110, 112 allow for the left and right articulationshafts 120, 122 to rotate relative to and around the proximal and distalring gears 110, 112 during the rotation of the knob housing 21. Further,since the projection 138 of the left housing half 120 a is received inthe left slot 144 a in the distal tube 24 b, and the projection 140 ofthe right housing half 122 a is received in the right slot 144 b in thedistal tube 24 b, rotation of the left and right articulation shafts120, 122 induces a corresponding rotation of the distal tube 24 brelative to the proximal tube 24 a, whereby the attached surgicalloading unit 30 is also caused to rotate about the longitudinal axis“X.”

Persons skilled in the art will understand that the adapter assembliesand methods specifically described herein and illustrated in theaccompanying drawings are non-limiting exemplary aspects of thedisclosure. It is envisioned that the elements and features illustratedor described in connection with one exemplary aspect of the disclosuremay be combined with the elements and features of another withoutdeparting from the scope of the disclosure. As well, one skilled in theart will appreciate further features and advantages of the disclosurebased on the above-described aspects of the disclosure. Accordingly, thedisclosure is not to be limited by what has been particularly shown anddescribed, except as indicated by the appended claims.

What is claimed is:
 1. An adapter assembly, comprising: a cam memberdefining a first cam slot and a second cam slot; an outer tube extendingdistally from the cam member and having a distal end portion configuredto be coupled to a surgical loading unit; a first articulation shafthaving a proximal end portion operably coupled to the first cam slot ofthe cam member, and a distal end portion configured to be coupled to thesurgical loading unit; and a second articulation shaft having a proximalend portion operably coupled to the second cam slot of the cam member,and a distal end portion configured to be coupled to the surgicalloading unit, wherein the first and second articulation shafts areconfigured to translate in opposite directions in response to a rotationof the cam member to articulate the surgical loading unit relative tothe outer tube.
 2. The adapter assembly according to claim 1, furthercomprising: a proximal ring member disposed about the cam member andhaving a projection received in the first cam slot; and a distal ringmember disposed about the cam member and having a projection received inthe second cam slot, wherein the proximal and distal ring members areconfigured to move axially in opposite longitudinal directions inresponse to the rotation of the cam member.
 3. The adapter assemblyaccording to claim 2, wherein the proximal end portion of the firstarticulation shaft is axially restrained to the proximal ring member,and the proximal end portion of the second articulation shaft is axiallyrestrained to the distal ring member, such that the first and secondarticulation shafts are configured to move axially with the respectiveproximal and distal ring members.
 4. The adapter assembly according toclaim 3, wherein the first and second articulation shafts are rotatablerelative to and about the respective proximal and distal ring members.5. The adapter assembly according to claim 4, wherein the proximal ringmember defines an outer annular groove therein, and the proximal endportion of the first articulation shaft has an annular protrusionslidably received in the annular groove.
 6. The adapter assemblyaccording to claim 5, wherein the distal ring member defines an outerannular groove therein, and the proximal end portion of the secondarticulation shaft has an annular protrusion slidably received in theannular groove of the distal ring member.
 7. The adapter assemblyaccording to claim 4, further comprising a knob housing disposed about aproximal end portion of the outer tube, wherein the proximal end portionof each of the first and second articulation shafts is non-rotationallycoupled to the knob housing and axially movable relative to the knobhousing.
 8. The adapter assembly according to claim 7, wherein the knobhousing includes an inner surface defining a pair oflongitudinally-extending slots, and the proximal end portion of each ofthe first and second articulation shafts has a longitudinally-extendingridge received in the respective pair of longitudinally-extending slotsof the knob housing.
 9. The adapter assembly according to claim 7,wherein the proximal end portion of the first articulation shaft has aninwardly-extending protrusion, and the distal end portion of the outertube defines a longitudinally-extending slot having received therein theprotrusion of the first articulation shaft, such that the distal endportion of the outer tube rotates with the first articulation shaftabout the longitudinal axis in response to a rotation of the knobhousing.
 10. The adapter assembly according to claim 1, wherein theproximal end portion of each of the first and second articulation shaftsis disposed about the outer tube and the cam member.
 11. A surgicalinstrument, comprising: a surgical loading unit; and an adapter assemblyincluding: a coupling mechanism having a drive shaft; a cam memberoperably coupled to the drive shaft and defining a proximal cam slot anda distal cam slot; an outer tube extending distally from the cam memberand having a distal end portion configured to be coupled to the surgicalloading unit; a first articulation shaft having a proximal end portionoperably coupled to the proximal cam slot of the cam member, and adistal end portion configured to be coupled to the surgical loadingunit; and a second articulation shaft having a proximal end portionoperably coupled to the distal cam slot of the cam member, and a distalend portion configured to be coupled to the surgical loading unit,wherein the first and second articulation shafts are configured totranslate in opposite directions in response to a rotation of the cammember to articulate the surgical loading unit relative to the outertube.
 12. The surgical instrument according to claim 11, wherein theadapter assembly further includes: a proximal ring member disposed aboutthe cam member and having a projection received in the proximal camslot; and a distal ring member disposed about the cam member and havinga projection received in the distal cam slot, wherein the proximal anddistal ring members are configured to move axially in oppositelongitudinal directions in response to the rotation of the cam member.13. The surgical instrument according to claim 12, wherein the proximalend portion of the first articulation shaft is axially restrained to theproximal ring member, and the proximal end portion of the secondarticulation shaft is axially restrained to the distal ring member, suchthat the first and second articulation shafts are configured to moveaxially with the respective proximal and distal ring members.
 14. Thesurgical instrument according to claim 13, wherein the first and secondarticulation shafts are rotatable relative to and about the respectiveproximal and distal ring members.
 15. The surgical instrument accordingto claim 14, wherein the proximal ring member defines an outer annulargroove therein, and the proximal end portion of the first articulationshaft has an annular protrusion slidably received in the annular groove.16. The surgical instrument according to claim 15, wherein the distalring member defines an outer annular groove therein, and the proximalend portion of the second articulation shaft has an annular protrusionslidably received in the annular groove of the distal ring member. 17.The surgical instrument according to claim 14, wherein the adapterassembly further includes a knob housing rotationally coupled to thecoupling mechanism and disposed about a proximal end portion of theouter tube, wherein the proximal end portion of each of the first andsecond articulation shafts is non-rotationally coupled to the knobhousing and axially movable relative to the knob housing.
 18. Thesurgical instrument according to claim 17, wherein the knob housingincludes an inner surface defining a pair of longitudinally-extendingslots, and the proximal end portion of each of the first and secondarticulation shafts has a longitudinally-extending ridge received in therespective pair of longitudinally-extending slots of the knob housing.19. The surgical instrument according to claim 17, wherein the proximalend portion of the first articulation shaft has an inwardly-extendingprotrusion, and the distal end portion of the outer tube defines alongitudinally-extending slot having received therein the protrusion ofthe first articulation shaft, such that the distal end portion of theouter tube rotates with the first articulation shaft about thelongitudinal axis in response to a rotation of the knob housing.
 20. Thesurgical instrument according to claim 11, wherein the proximal endportion of each of the first and second articulation shafts are curvedand disposed about the outer tube and the cam member.